If you can learn, yeah, so, yes. Do you hear me? Yeah, me Okay. Yes. Okay. Very
good. So let's start.
I'm going to start this, this presentation with a couple of introduction slides, but
fabulous body Seder quite a lot about these. So we, given its unique properties
of course, dockworker presents an important research topic at the at the
LSE. The important most massive element pi particle has also, its particularity of
decaying before. tokenizing also allows us to study bear Kwok through through the top
walks in 3d represent an important probe for boost testing the standard model and
peace and physics, testing pressure but if you see the next to next reading or the
precision constraining button distribution functions determining standard model
parameters, studying rare processes and costs training new physics and through
indirect measurements of admittance couplings or died surgery.
For heavy residencies coupling to the top cook.
This is an article evidently produced at the LSE, as you mentioned. So in this
presentation, I'm going to focus only on the dominate dominating production mode.
So, the Tiki Bar pair production is dominating here mostly through going
through infusions. And unless I extend There is also single production with the T
channel, the Tw SSAT production and N dS the S channel for the rare process either
invite you to follow leadership willingness to really develop
this product predictions.
So in first sections, then the core of the
investigations on the top core concern the core production, and here are summarized.
Overview of the recent inclusive and differential cross section measurements
here. Let's see
But first we have to just remind that basically we have three main
investigations channels to perform such such measurements which depends on the
final state of the city bar there you can access with your detector. So, first we
have the dialect and channels, the keenest signature, but also the the lower signal
statistics is a low branching ratios, where you have the most precise results in
the new final stage where you can mitigate some background contamination especially
the or Fulton's who, today lepton backgrounds, we have wt backgrounds, fake
leptons, dye bosons and Z to toto.
On the other hand, we have the the lepton plus jet channel which is a compromise
between signal statistics and background contamination. Here we are mostly the
community by channel processes that will use Jetson with the Jets. But he had given
the largest statistic we have the possibility to exploit multi
To control regions to constrain systematic uncertainty, finally, we have the whole
alternate channels with a larger branching ratio, but also the significantly less
precise channels essentially due to the large richer background uncertainty and
but here we have some possibility to explore for instance, highly boosted top
box and get complimentary information. In terms of systematic uncertainties, such
measurements are dominated by the signal modeling uncertainty.
The object efficiency in calibration, leptons jets flavor tagging, in general
the background estimates and also the luminosity. Getting back to the signal
modeling. There are it's really a challenge for for precision measurements
where different strategies are developed by the different collaborations plus in
CMS, they look being uncertainties on Generate or shower modeling metrics so
element to potential matching asi for SAR, PDF, and so on.
There is a lot of discussion being seen in order to convert on common prescriptions
in order to make comparisons between the conversion results and future
combinations.
Right eight, an overview of the state of the art of the T bar cross section
measurements. So since the beginning of the 60s with a Chanel's many measurements
performed by the Atlas, TMS, and motion clearly CB collaboration, we found an
impressive agreement between the predictions and our measurements. So here
on these plots, you have the inclusive study by cross sections function of the
center of mass energy
measurements from Atlas and CMS and also have to consider new measurements formula
CV looking at for work to develop their projections complimentary to face pay that
Atlas or CMS can access.
So in terms of the
Latest inclusive measurements we have first results here from Atlas first result
exploding the full run to data set one on 114 investment to them. Since an increase
even finish with the bulk cross section measurement electron preset certain TV The
idea is to select one agents with one lips on electro neum keys for jets was swampy
tech jets and perform the combined profile I can fit two different kinematics
minimizing the systematic uncertainty effects in different single regions. So
here on the bottom left you have an illustration of the the minimal lift and
jet mass distributions on the left in here the the average angular distance of the
three jets of the selected the
three jets
in the evens
we have an analysis dominated by TT Bosch our journeys ation salvation and search
To deliver of 2.6% and also jet reconstruction 2.4% for final measurements
combined measurement reaching a precision and 4.6% which is compatible with the
latest theoretical predictions
it's like 10 of them and as a measurement here the first measurement from CMS deeper
in the dial it in
evens containing one time leptons certain TV there is similar you select one leptons
key three jets and in the three jets you look for keys one digit and one jet
identify the f1 key decaying tell it same strategy or profile like you'd fit this
time on the transverse mass of the liftin missing t distribution, where this is
split into different kinematics region based on the distance. The average
distance in the jet triplets you have selected and Ito and youtell finally
states.
Here the dominating systematic systematic
How jet lagged and indentification uncertainty. We are also affected by the
luminosity, the teapot background normalization and the pileup at the end we
reach a prediction of precision of 8.3%. Here again compatible with the the latest
theoretical prediction. And we add also a number of extraction of
additional information showing for instance, the consistency of the lip and
universality by computing the ratio between these the LTL towel mode versus
the dial over dialects and modes. Also an improvement from the partial decay which
the town the public came to tell you be vehicle back to previous measurements.
Slide 11
one of the latest results in development evens by a class for an exclusive and let
them differential measurements. So here the idea is to select easily to proceed
signing new pair and one or two in one or two beats in one or two digits and
Perform content count analyses based in these two, one and two B tech channels,
and from them extract the TT bar cross section measurement from the feet of these
values. On top of that, there is a split in the data campaign through a no blue
iterative combination between 2015 2000 data in order to make use of the
uncorrelated uncertainties
between the different campaign leading to significant reduction in total
uncertainty. At the end, the dominant systematics is the luminosity and then
let's extend the background cross section and Tiki Bar shower and naturalization and
as I said, we reach here procedure of 2.4% which is the most precise measurement at
the elite See, here again fully compatible with the latest theoretical prediction.
Slide 12 a bit beyond just measuring the TT bar cross section we can also consider
TT barbarous adventure.
Radiation so he it's a new result from the latest result from CMS about the inclusive
measurements of the TT bar plus jet jets cross section and the ratio between these
cross section D bar is BB bar. So, this is measuring the fuel face space. So, through
a profile I can fit to the B tagging discriminant distribution of these
additional jets. This allows to infer directly on the titty bar plus b bar cross
section and this is extrapolated to the to the to the to the full face space through
an acceptance corrections. On the left you have the summary of these measurements for
the ratio in the to cross section. At the end we have inclusive TT BB v cross
section and cross section ratio slightly higher than the prediction the CIF
consistent with the multicolor generator predictions and we reach precision around
13 to 12%. The Tiki Bar BB bar cross section in perspective in dialects and in
getting this channel
Another new results is the evidence for the Tiki Bar production elite collisions
by CMS the energy of that of mass five TV here this dyslexic to select Liberty sign
at least one sign in new pair cooling leptons and electron the new ones and two
B tech jets and here same strategy profile like you'd fit to VDD distributions in
different electronic categories with or without the tagging
jet multiplicity information
we reach a 4.0 sigma and three point hating main both of these these categories
and and at the end we observed usual cross section slightly lower but see compatible
with some scale proton proton data expectation and, and theory calculations.
On the left you have on the right you have this illustration of search results with
the cross section nominations.
To the
to the mass number to the squared here.
So then beyond the inclusive,
the inclusive measurement needs to move forward to move towards the differential
measurements which really stands as the interface between the state of the art of
the theory calculation, much color generation and the experiments. It's
allows us to give a strange test on perturbative theories, several observable
of sensitive to different effects, metric elements, radiation hybridization. It's
also a nice tool for us to improve our simulation, attuning aeronautical
engineering, and also probe new physics, not modifying receive cross section
essentially via an effective field theory interpretation. And in this game, the
unfolding of detectable observable measure in physical face space to particle
particles, and that's really at the heart of the measurement strategy. And to
illustrate a little bit decent
Next slide.
Our availability of computing and ninefold the number of events is based on our
understanding of the acceptance effect of our detector. The migration between the
particle the detectable observers versus the particular pattern level observables.
Also, additional connections on the efficiency can be, can be done, apply to
access to a full face space if you want to compare to later theoretical prediction,
for instance, but as soon as you have this number for funding event, it's really easy
to build differential cross section by normalizing to the cross section to the
luminosity or the being of your favorite kinematic distribution.
Among the latest results, here on slide 16, there is the last part of the
intuitive measurement dialect events that I mentioned above for my class here
looking at lepton differential distributions. So the exactly the same
strategy
Team events but he's been afflicted kinematics and performing differential
cross sections and compare particle level prediction to choose the data. So, here
you have an illustration of the Lipton PT.
On the left and on the right you have different ratios between several
predictions and the data. In general from these studies among the main conclusion,
we have seen software like bt and move forwards EDA distribution in data, but
this leptin PT can improve could be improved. In some Monte Carlo was set up
essentially and set an ELO plus API especially using our PDF. Now looking a
bit closer to the top Quark distribution There was a recent result from
differential double differential democra section Neptune preceded by a class
exploring both resolved and boosted topologies first slide here on the the
results topology, selecting one Lipson and that is for jet with the keys to detect
jets. So here we have on the left
The castration of the PT on the top here
at officials face base so here again we have confirmation that put peg with PJ
it's best to describe the top PT distribution but moving to the full face
space and going a bit beyond that just the differential measurement but looking at
the double differential measurement we're able to reveal some discrepancy between
data and multicam. So, on the right you have an illustration where you have the PT
of the TT bar distributions in the middle which looks okay
in differential measurement, but on the right when you been in terms of
environments with Tiki Bar system, you see the discrepancy exhibiting from from from
the last
few words about the boosted topologies here so the idea is similar but instead of
selecting
separately jetty looks at one additional
Larger jet which is clustered the requested form a smaller jets here with a
certain number of selections to to identify these jets as jets compatible
with the the top Quark and here we have similar comparison but generally
kinematics okay but a high matter reason few discrepancy for some prediction. There
is also a comparison between resolve and boosted regime where good overlap between
both has been observed even if the full comparison is a bit difficult since the
the definition of the object at particle level is slightly different.
In slide 19 similar results a new result from from CMS and the differential to
debug cross section IPT top cork here were the the investigative these slides here
the leptin plus jet final set was a one large object one lips on one vitek jets
and perform against some absolute and normalize differential cross section
measurement. Here you have an illustration on the PT of the top
The the rapidity of the topic in general the the distributions generally will
describe even if some models over predict in general the absolute cross section by
another 20%
going to be beyond in these multi differential exercises, CMS published a
recent results here where they, they looked at lots of different multi
differential distributions
and produce a normalized cross section, measure the main opposite sign up for
events where the main conclusions were that no predictions were able to describe
all distributions on the right you have an illustration of the p value of the chi
square test of different Monte Carlo prediction for the different distribution
investigated. And going back to the top PT they observe the soft top PT distribution,
especially against in this high Tiki Bar mass
going one step beyond There is also the first triple differential measurement by
CMS here in stration. Consider the normalized 30 normalized
differential cross section as function of the rapidity of the TT bar system and
being in term of environment. So, the Tiki Bar system and the number of additional
radiation. So, in general prediction looks okay up to energetical one and we have for
more complex final states. Some advantages from Piquet again in the description of
such such kinematics slide 22 a bit closer about the old 20 finest day there was a
new result from differential double differential cross section measurement
from a class. Here it's in resolve topologies. So, the selecting events
recently suggests is to detect jets and perform similar a similar scene.
Like the size
differential cross section at particle and baton level, in general, there are nice
modeling the hardness of the leading three jet emission leading to the top PT in the
top top, the Tiki Bar PT distribution compatible with several theory prediction
at these at it is illustrated on the left here with the differential distribution
and here on the right with the the double differential distribution which really
exhibit where in the kinematics you have the most important discrepancies.
Slide 23 a complimentary of the result I mentioned the new results of this
differential feedback cross section IPT. But these are fully identified states
where by CMS we have two large objects are selected. In here we have similar
conclusion but we observe the more prominence over predictions on the
absolute cross sections level of 35% for the different models have been straight
here on the two plus PT of sudden suddenly
tops in the Tiki Bar mass, but in general the the the description is consistent and
different differential distribution.
So now just to come to conclude, the last part is dedicated to also recently fought
on the single core productions. Now I want you to I like to results
on these but first of all here an overview of the state of the art of what's being
performed in, in this sector by a classic TMS. So again, lots of measurements, the
prediction here also impressively impressively in agreement with the
measurements. And in order to get even better precision on this measurement,
there is also the idea of combining the result and the purpose of this first slide
about you fought combining runway measurements, where the team performed the
group combinations of the 10 inclusive measurements production and setting
have less energy. Here the difficulties to care take care of the experimental
uncertainty and correlation which exists between the different sources but also
between the experiments where there's lots of works behind the scene, this and we
have
finally final combination which is dominated by theory, analytical modeling
jet reconstructions. And in case of these external data statistics, at the end, we
have measurements reaching combined measurements reaching precision of 8.4 and
25% for T and wt channels at 70 V, and 6.8 16 and 30% respectively for t wt s
channel at a TV.
On top of combining cross sections, there is also a combination of the VTB secant
parameters.
This is being determined for each production but also the full combination
of orders
All reasons that leads to better come combined VTB to the square and even to the
linear dependence with the cross section. And he had systematic uncertainty
dominating his theory theory modeling, theoretical cross sections and the d'etre
constructions at the end. This exercise this combined measurements which are
precision of 3.7%, which is driven by the T channel cross section measurements.
Finally, one last result in your result from from CMS with a differential 30
minute differential Tw cross section in dialog engines,
where it needs to select here, emu pairs
and perform an even classification based on jet and detect jet multiplicities has
illustrated on the bottom with this distribution here and perform a normalized
differential cross section measure that's found
Also several values properties.
And here the systematic uncertainty community by the jet reconstruction, the
theory modeling and of the TT bar background which is really dominating here
the Select events.
to to to conclude one last slide with the illustration of some of the kinematics
investigated here you have the jet bt delta phi between the electron and the
moon and the transverse mass of the Tw system here which is where they are
compared to two different Tw signal prediction based on po egg and Metcalf
Sienna Luca speciate. And here we have consistency between the prediction and the
end and the data.
Finally, one summary so the Alexi run one and run to provide you the high statistics
Core Data
Many precision measurement perform until now.
Recent measurements have confirmed our good agreements, model expectations,
improving precision, for instance, exploiting larger data statistics or via
some combinations between the different experiments and also probing new
kinematics regimes especially in highly boosted state. We also have a better
understanding of the physics modeling and detector effects we've had the end
represents the largest experimental uncertainty and real challenge for
precision measurements. And in this society, the differential cross section
measurement is really at the heart of the latest investigation. And in particular,
the, the multi differential measurements give very powerful insights and extremely
useful for improving our multicolor predictions. That's all from my side.
Thank you very much for your attention. Thanks, Jeffrey, for the nice talk. So we
are open for questions now.
Please say your name and institution and raise your hand.
I think we have one question from Lisa.
You had unmuted your panelists, so you can go here. Yeah. Okay, isn't it there's
somebody in the University of Goodson Atlas.
Thanks, Jeffrey. Very nice talk a lot of information. And so the you presented this
new measurement of tiki bar plus heavy flavor from CMS.
Maybe it was too fast. So, my impression is that compared to the previous
measurement, where CMS measures the ratio of TT BB to teach your change, say, of the
factor of 1.7 with uncertain 0.3 I think that these new measurements do not show
such big ratio or
Am I wrong
with respect to enhancement of TT BB with respect to TT? Jj
there is no such plot. Okay, here it is ratio
is yes. You have the previous, the previous measurement here, right. Oh,
okay. Okay, good. Yes. On the bottom left, you see which is slightly slightly lower.
That's also the uncertainties. It's like you reduced
because they changed the procedure now they treat the systematics in terms of
through the profiler, like you'd fit as reasons parameters and also restrict to
beat the bounds.
Right. So this factor changed, in fact, right from based on the recent
measurement.
Thanks.
Other questions?
I don't see any other
Hands rate, I do have a question. And for the case for the inclusive lead complected
TTR cross section that with 100 foot run to measurement from Atlas. Yes, these one.
So what is the luminosity? So there are two questions. What is the luminosity
uncertainty in the systematics that in the systematics, what is the
proportion or the ratio? What is the number for the luminosity here? And are
you profiling here? The luminosity and in the dilettante are not in the dialect on
that is a few pages after this one. Are you doing the same treatment for the
luminosity in both analysis? So first of all, the luminosity is at the level of
1.7%, if I remember correctly, and then for the profile link of this nuisance
parameter. I'm not completely sure. I would say I would say not but maybe
someone can confirm
Yes, we do profile this, but this uncertainty is not moved or constraint.
It, it stays as is and it doesn't, in fact, when it does belong to high amounts
at the analysis is fully dominated by the teacher by modern humans
fully, but I mean, it's one of the major uncertainties and luminosity a number
three or four, number three or four, but it's the treatment different than the four
that I left on China that what you're doing in a few pages after the
Yes, the treatment is different in the sense that
dialectic dialect on in general, they
it's a combination of 2015 and 2016. Right, and to them for 2015 aluminous.
Down 70 was significantly larger. That's why these two data sets are
Combined by blue, not by applying average element Austan certainty for 2015 and 2016
because it would have been significantly larger than in the laptop analysis, but
also the luminosity is not proof I mean, this is my yes nothing is profiled in this
Yes, in this one but in the other one it is it is yes. Okay.
there any other questions?
Okay.